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F - 248 : Climate Change stopped the Mongols

We write the year 1241/42. The Mongol Army had just wiped out the Polish and Hungarian Knights and took winter quarters in the low lands of Bulgaria. On the Bosporus’ other side, a different Mongol Army had crushed the Turkish Seljuks a year earlier. The Turkish nemesis, who had pushed Byzantium out of Anatolia, was gone. The days of the shrunk Byzantine Empire now seemed numbered. The fall of Constantinople, still ruled by Venice, imminent.

This Illustration is almost realistic except. that Mongol Cavalry attacked from a safe distance from where it could fire Volleys of Arrows without Exposure to the Knight's Cross-Bows

1261, a mere 20 years later, the Byzantine Empire was back. The Venetians were kicked out. Constantinople was Byzantium’s capital again. Its port was busier than ever. Merchants from Genoa conducted trade between the Mongols, Europe and the Egyptian Mamluk, the rulers of the Levant since 1250. Genoa, the Crimea and Alexandria were the end points of this trade, the harbor of Constantinople and Galata its staple place. For almost 100 years, until the Plague struck in 1347, Byzantium and Genoa made money as never before.

Constantinople in the 13th Century with its Natural Harbor (Golden Horn) between the main Town and Galata, the Genovese Colony, opposite

Militarily, the Mongols and the Mamluk kept the defeated Turks in check. They had clashed not far from the Sea of Galilee in 1260 and now respected each other. The Mongols were the overlord over several small Turkish Beylics and had a garrison installed in Ankara (some of the Mongolian graves can still be seen). To strengthen the Mamluks, the Mongols sold them Caucasian slave boys for their army and slave girls for the harems. The Genovese Merchants happily obliged to transport both from the Black Sea to Egypt. As long as they were not Christians, who cared?

Under Mongol Rule, for the only Time in History, Europe and China had a common Border. The shaded territories were temporary Mongol Conquests

It was the first time in history that Europe had a direct link to China. On Genovese ships, Italian merchants like Marco Polo and a few clergymen sailed to the Genovese colonies in the Crimean. From there they trekked all the way to Beijing, a journey that took a year. The silk road was the busiest commercial road in the world with well-maintained inns and well protected by Mongol soldiers. Silver travelled East - silk, china, tea and gun powder West. It was also an avenue for technology transfer like the printing press, astronomy, paper, or the iron plough which would transform Europe as it allowed the cultivation of heavy soils in its northern and eastern parts.

The Re-established Byzantine Empire in 1265 AD

But why did the Mongols stop in 1242 choosing trade over conquest? With their army of 150’000 men standing at the banks of the Oder and the Danube, controlling Hungary and having their winter quarters only a hundred miles from Constantinople, they were in the heart of Europe. Why did they not finish the conquest and push into The Holy Roman Empire (Germany and Italy), France and then Muslim Spain? The German and French Knights were no better equipped to stop the Mongols than their Polish and Hungarian comrades.

The formal explanation was the succession of Ögödai, the Mongol Kahn who had died in December 1241. The appointment of a new Khan required the presence of all major Mongol princes in Karakorum, the Mongol capital. But after a temporary withdrawal of a year or two, the Mongol army could have returned – why did they not?

In 2016 the Science Magasin Nature published an Article "Climatic and Environmental Aspects of the Mongol Withdrawal from Hungary in 1242 AD"

As we now know from studies on climate history, the European weather became wetter and colder towards the middle of the 13th century, exactly at the time of the Mongol invasions. This created an insurmountable problem for the Mongols. With an estimated army size of 100’000 – 150’000 men (there was only cavalry, no infantry) and each cavalryman having 2 or 3 horses (one to ride, one to change, one to eat) there were almost half a million horses to feed. This was already a big challenge in the vast steppes of the Ukraine. In Central and Southern Europe, it was impossible.

The Hungarian Castle of Spis, now in Southern Slovakia. Taking Hungary's many strongly fortified places would have required a prolonged military campaign

Map also taken from Nature - the Blue Dots represent the Hungarian Castles the Mongols could never conquer. Red Lines = Mongol Advance, Blue Lines = Mongol Retreat

By the 13th century, considerable parts of Germany and Poland were still forested without large-scale food production (yet). In the Balkans with its karst mountains, the situation was as dire – as we noticed when sailing along the Dalmatian coast in 2019. The only suitable places with sufficient supplies for the Mongol Army were the Hungarian and Bulgarian plains – good for one winter possibly but too small for a permanent presence. The Mongols were thus constrained by geography – not only in Europe but also in the Levant where the semi-arid climate imposed similar constraints. Add the continued resistance of Hungarians in their heavily fortified castles, which would require a prolonged military campaign. In other words, Mongol expansion had met the limits of its logistics.

As the Genovese Trade Routes from the 14th Century illustrate, Trading with China via Silk Road and the Black Sea had overtaken the Old Routes via Red Sea and Persian Gulf

The halt of the Mongol advance gave Europe breathing space and ushered in almost 100 years of prosperity. The iron plow opened new space for cultivation, newly founded towns allowed division of labor on a large scale and trade routes dormant for centuries were reopened. Europe was not rich (yet) but the nobility and towns people could afford imported goods from Asia again. Genoa and Venice prospered. Despite the loss of Constantinople in 1261, Venice was still a formidable commercial and military power. Genoa became the Mongols most important trading partner and established colonies all around the Black Sea. It benefited significantly from trading privileges Byzantium had granted in 1261 but this is the story of the next blog.

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